The invention relates to a process for producing a BGA (ball grid array) type semiconductor device having a structure comprising a semiconductor chip and solder balls mounted on a TAB (tape automated bonding) tape, a TAB tape for a BGA type semiconductor device, and a BGA type semiconductor device.
A BGA type semiconductor device is known as a semiconductor device having such a structure as directly mounted on the surface of a substrate with the aid of solder balls. In this BGA type semiconductor device, electric connection to the substrate can be made on the whole area of the plane portion in the package. Therefore, unlike QFP (quad flat package) and the like wherein connection is made in each side of the package, multiple pin (multiple port) can be advantageously achieved without narrowing lead-to-lead (terminal-to-terminal) pitch. In particular, use of a TAB tape as a structural material for the package can realize a reduction in thickness and a reduction in size (chip size package).
The conventional process for producing a BGA type semiconductor device comprises the steps of: mounting chips on a TAB tape; performing inner lead bonding, resin sealing, and ball mounting in that order; and finally punching out four peripheries of the TAB tape at a time using a die.
The conventional production process of a BGA type semiconductor device will be explained in more detail.
A TAB tape of a resin film has on its both sides sprocket holes at given intervals, and semiconductor chips are mounted at given intervals on the TAB tape in its center portion. The semiconductor chip is mounted with the aid of an elastomer having an adhesive surface. The fixed semiconductor chip in its electrode pad (in this example, two pads in upper and lower hems) is connected by bonding to an inner lead provided so as to project from the TAB tape. In order to protect the inner lead, plastic molding is carried out using a resin sealant. A plurality of solder balls are two-dimensionally and regularly mounted on a wiring pattern provided on the TAB tape in its side opposite to the semiconductor chip-mounted side. Finally, cutting from the TAB tape is made semiconductor chip by semiconductor chip.
The construction of a semiconductor chip-mounting portion will be explained in more detail. A belt-shaped opening through which an inner lead is to be passed is provided in the TAB tape. After bonding, the opening is subjected to plastic molding with a resin sealant.
The procedure for producing a BGA type semiconductor device will be explained. At the outset, semiconductor chips are applied through an elastomer onto one side of the TAB tape. Next, the semiconductor chip in its electrode pad is connected by bonding to an inner lead on the TAB tape side, and plastic molding is then carried out using a resin sealant to protect the bonded portion. Solder balls are mounted on a wiring pattern at its predetermined positions. Thereafter, four sides of the TAB tape at its cutting position are simultaneously cut using a die to obtain one package.
Another conventional BGA type semiconductor device is described, for example, in Japanese Patent Laid-Open Nos. 31869/1996 and 153819/1996. In the BGA semiconductor device described in the former publication, device holes are provided in a TAB tape. A plurality of electrode pads for electrode bumps (solder balls) connected to an inner lead are interspersed around the device holes. Elongate cut holes are provided on four sides around the pad region. After the formation of the electrode bumps and before mounting onto a mount substrate, cutting is performed in the cut hole portions to separate semiconductor devices from each other or one another. On the other hand, in the BGA type semiconductor device in the latter publication, a semiconductor chip is mounted on a mount substrate so that the electrode-forming surface of the semiconductor chip faces upward. The wiring pattern on the upper surface of the substrate is connected thereto by wire bonding. A part of upper and lower wiring patterns in the substrate are connected to each other with the aid of through-holes. Solder balls are mounted on the lower wiring pattern. As with the semiconductor device disclosed in Japanese Patent Laid-Open No. 31869/1996, the elongate holes provided on the outermost periphery are used as sites for cutting out and separating semiconductor devices from each other or one another before mounting onto the mount substrate.
In the conventional processes for producing a BGA type semiconductor device, the whole periphery of the package is simultaneously punched out at the time of the separation of semiconductor devices from each other or one another. Therefore, stress is likely to be applied to the adhesion interface of the TAB tape and the resin sealant or the semiconductor chip and a joint between the semiconductor chip in its electrode pad and the lead, leading to separation of the joint and cracking of the sealing resin. This often lowers the reliability of the package.
Since the TAB tape is continuously present on the outer periphery of the semiconductor chip, plastic molding using a liquid resin causes a variation in wetting and spreading of the resin in this portion. This results in uneven thickness of the finally formed sealing resin layer. Specifically, excessive wetting and spreading of the liquid resin cause an excessively small resin layer thickness. Likewise, when the resin is wetted and spread to the cutting position of the TAB tape (outward line of the package), the final cutting step creates cutting of the resin together with the TAB tape. This also leads to the breaking of the joint, that is, the separation between the electrode pad and the lead, and the cracking of the sealing resin, often resulting in lowered reliability of the package.
In the BGA semiconductor devices disclosed in Japanese Patent Laid-Open Nos. 31869/1996 and 153819/1996, the adhesion interface and the joint are located inside each of the solder ball. Specifically, the solder balls are provided so as to surround the semiconductor chip. According to this construction, a problem of the breaking of the joint, that is, the separation between the semiconductor chip in its electrode pad and the lead, and the cracking of the sealing resin attributable to the application of stress can be avoided.
Accordingly, it is an object of the invention to provide a process for producing a BGA type semiconductor device, a TAB tape for a BGA type semiconductor device, and a BGA type semiconductor device that can offer high reliability while reducing the thickness and the size of the package.
According to the first feature of the invention, a process for producing a BGA (ball grid array) type semiconductor device, comprises the steps of: forming openings around each chip-mounting region in a TAB (tape automated bonding) tape while leaving linking portions for connecting the chip-mounting regions to the other region; mounting a semiconductor chip on each of the chip-mounting regions in the TAB tape; connecting, by bonding, the semiconductor chips each in its electrode pad to the TAB tape in its wiring pattern; subjecting the bonded connection between the semiconductor chip and the electrode pad to plastic molding with a resin; providing solder balls on the backside of the TAB tape in its portions corresponding to the chip-mounting portions; and cutting off the linking portions to provide discrete semiconductor devices.
According to the second feature of the invention, a TAB tape for a BGA type semiconductor device comprises a large number of solder ball-mounting holes provided in chip-mounting regions, wherein an opening is provided around the chip-mounting region while leaving a linking portion for linking the chip-mounting region to the other region.
According to a third feature of the invention, a BGA type semiconductor device is produced by a process comprising the steps of: providing a TAB tape for a BGA type semiconductor device, comprising a large number of solder ball-mounting holes provided in chip-mounting regions, an opening being provided around the chip-mounting region while leaving a linking portion for linking the chip-mounting region to the other region; mounting a semiconductor chip on each of the chip-mounting regions in the TAB tape; connecting, by bonding, the semiconductor chips each in its electrode pad to the TAB tape in its wiring pattern; subjecting the connection between the semiconductor chip and the electrode pad to plastic molding with a resin; mounting solder balls on the solder ball-mounting holes in the TAB tape; and cutting off the linking portions to provide discrete semiconductor devices.